Drain-extended (DE)-MOS transistors are used in diverse high-voltage applications, such as power RF and driving piezo-electric ultrasonic transducers. Such transistors are generally characterized by relatively high breakdown voltage between the drain and the substrate. However, some existing DEMOS transistors, in particular DE-PMOS transistors, are limited to a breakdown voltage less than about 50V. This limit makes DE-PMOS transistors unsuitable in some applications.